Charles is a web proxy (HTTP Proxy / HTTP Monitor) that runs on your own computer. Your web browser (or any other Internet application) is then configured to access the Internet through Charles, and Charles is then able to record and display for you all of the data that is sent and received.
Features
・SSL proxying: view SSL requests and responses in plain text
・Bandwidth throttling to simulate slower Internet connections including latency
・AJAX debugging : view XML and JSON requests and responses as a tree or as text
・AMF: view the contents of Flash Remoting / Flex Remoting messages as a tree
・Repeat requests to test back-end changes
・Edit requests to test different inputs
・Breakpoints to intercept and edit requests or responses
・Validate recorded HTML, CSS, and RSS/atom responses using the W3C validator

What’s New in Version 4.0.2:

Bug fixes and minor improvements
・Local IP addresses are now sorted, and the window is bigger
・Fix display of local IP address in SSL Proxying remote browser help
・macOS: Improve occassional hanging issue when using a retina display
・macOS: The window can now be dragged by the title label, and not when fullscreen
・Windows: larger toolbar icons
・JSON import/export: include exception details
・Focussed setting now remembered in Sequence view
・Antialias text on Chart view